Internal coil magnetostrictive transducer

ABSTRACT

An acoustic waterproof transducer of a thin magnetostrictive strip formed into a closed loop and having a pressure release material against one surface thereof. An electrically conducting wire is continuously loop wound within said closed loop transversely and disposed in a waterproof jacket. The entire structure is formed into a longitudinally extending loop transducer.

United States Patent Inventors David E. Parker Pawcatuck; Thomas L. Beaudoin, Mystic, both of Conn. Appl. No. 851,965 Filed Aug. 21, 1969 Patented Nov. 2,1971 Assignee The United States of America as I represented by the Secretary of the Navy INTERNAL COIL MAGNETOSTRICTIV E TRANSDUCER References Cited UNITED STATES PATENTS 2,472,388 6/1949 Thuras 340/11 2,749,532 6/1956 Harris..... 340/11 2,761,118 8/1956 Wallace...., 340/11 Primary ExaminerRodney D. Bennett, Jr.

Assistant ExaminerBrian L. Ribando Attorneys-Louis A. Miller, Louis B. Applebaum and Ernest F. Weinberger ABSTRACT: An acoustic waterproof transducer of a thin magnetostrictive strip formed into a closed loop and having a pressure release material against one surface thereof. An electrically conducting wire is continuously loop wound within said closed loop transversely and disposed in a waterproof jacket. The entire structure is formed into a longitudinally extending loop transducer.

4 Claims, 2 Drawing Figs.

U.S. Cl 340/11 Int. Cl H04r 15/00 Field of Search 340/1 1 zvz'zva iflz'l I rae'zylliasm INTERNAL COIL MAGNETOSTRICTIVE TRANSDUCER The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to underwater communication and more particularly pertains to waterproof line magnetostrictive transducers and hydrophones wherein the coil winding is internal.

2. Description of the Prior Art In the field of underwater communication it has been the practice to employ transducers and hydrophones of the unitary and solid variety wherein the sensitive structure is relatively rigidly mounted. Such devices have been unsatisfactory in that their length and therefore their utility have been restricted. The present invention fills this need in that it can be economically fabricated in a continuous manner and restricts the coil winding to within the magnetostrictive element.

SUMMARY OF THE INVENTION The general purpose of this invention is to provide a hydrophone that has all the advantages of similarly employed prior art devices and has none of the above described disadvantages. To attain this, the present invention provides a unique structural magnetostrictive line hydrophone which comprises a series of continuous loops of an electrical conductor which is surrounded by a pressure release material. This entire conductor loop is waterproofed with a flexible material and overlayed with a nickel strip to form a closed loop transducer.

An object of the present invention is to provide a reliable, inexpensive and simple magnetostrictive transducer.

Another object is to provide a waterproof line transducer which may be readily fabricated in any desired length and used with as many active elements as necessary.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates the completed loop transducer made in accordance with the principle of this invention; and

FIG. 2 is a view taken approximately along line 2-2 of FIG. 1.

DESCRIPTION OF A PREFERRED EMBODIMENT In the illustrated embodiment of FIG. 1, a magnetostrictive transducer 10 in the form of a closed loop is provided with an outer annealed nickel strip 11 which is wound helically about an inner core. The nickel strip is annealed at approximately 900 C. The core comprises a plurality of coil loops forming a winding 12 of insulated copper electrical conductors 13, the ends 14 and 15 of which extend outwardly thereof. Enclosing the winding 12 is a tubular layer of a pressure release material 16. (The pressure release materials in general presently available include corprene, cork and paper. The selection of a particular material depends essentially upon the depth or pressure to which the transducer will be subjected under operating conditions.) The pressure release material completely surrounds and tightly abuts the winding 12 so as to be in intimate contact therewith. Disposed circumfer'entially about the pressure release material 16 is a waterproof coating or layer 17 which may be of rubber or corprene. This tubular layer protects the inner elements against the intrusion of moisture and sea water. Spirally wound about the aforedescribed structure is the strip of annealed nickel 11 which serves as an active transducer element.

The ends of the wires 14 and 15 are electrically joined to similar wires 18 and 19 of a waterproof cable 20 and the entire junction, including a portion of the transducer, is encapsulated in a waterproof matrix 21. The cable 20 is employed for coupling to a remote receiver.

FIG. 2 illustrates in cross section the transducer structure with the configuration of the copper wires. In a successfully fabricated transducer, 40 strand number 26 copper wire was used.

We claim:

1. A magnetostrictive transducer which comprises:

a continuously loop wound insulated electrical conductor having ends thereof extending outwardly thereof,

a layer of pressure release material surrounding said loop winding,

a layer of waterproofing means enclosing said pressure release material, and

a thin strip of magnetostrictive material spirally wound about said layer of waterproofing means,

whereby said ends may be connected to a remote receiver.

2. The transducer according to claim 1 wherein said pressure release material is corprene.

3. The transducer according to claim 2 wherein said magnetostrictive material is annealed nickel.

4. The transducer according to claim 3 further including:

a waterproof cable,

electrical junction means connecting said ends with said cable, and

encapsulating means surrounding and enclosing said junction means and waterproofing the same. 

1. A magnetostrictive transducer which comprises: a continuously loop wound insulated electrical conductor having ends thereof extending outwardly thereof, a layer of pressure release material surrounding said loop winding, a layer of waterproofing means enclosing said pressure release material, and a thin strip of magnetostrictive material spirally wound about said layer of waterproofing means, whereby said ends may be connected to a remote receiver.
 2. The transducer according to claim 1 wherein said pressure release material is corprene.
 3. The transducer according to claim 2 wherein said magnetostrictive material is annealed nickel.
 4. The transducer according to claim 3 further including: a waterproof cable, electrical junction means connecting said ends with said cable, and encapsulating means surrounding and enclosing said junction means and waterproofing the same. 